Githyanki: I'm one of the old-time 1970-1980s pen and paper D&D players, and Githyanki are a Lawful Evil race.
That said, with the current companions available it is very difficult to create a viable 4-person party. You are stuck with certain choices--you pretty much HAVE to bring the vampire rogue, unless you roll a rogue, and you HAVE to bring the sassy cleric (unless you roll...) and same for the Gith fighter. A 5 person party would give you a lot more choices as to what you wish to bring. Larian added Druids, which required a lot of game rework, but didn't necessarily solve the "4 person party" conundrum. A Paladin class might have, thus eliminating the need for the Warrior and/or the Cleric.
How about next patch you do a bunch of game rework and re-balance the encounters for a 5 person party?